Suspension type work platforms are well-known in the art. They are traditionally mounted from the roof or upper stories of a building by means of temporary roof beams or permanent mounting davits, and often employ a track-based roof carriage, or monorails, to provide movable anchoring points for a work platform system. Obviously, a roof-mounted suspension platform system requires a usable roof, and therefore such a design is inherently unusable for a vertical structure under construction, for structures having a roof covered in large part with mechanical equipment for the HVAC system, or for a sloping roof. Alternatively, work platforms may be raised from the ground by means of a lift, such as seen in various “cherry-picker” type work baskets; or with a scissors-like arrangements as seen in U.S. Pat. No. 4,114,854; or by means of an extending tower, as seen in U.S. Pat. No. 4,068,737. These ground based systems have the advantage of easy mobility, but all share the obvious shortcoming of being severely limited in the height to which the platform may be raised, which is generally limited to a very few stories of building elevation.
Alternatively, ground based systems may utilize scaffolding supports that are built-up from sections in order to reach variable heights. A typical example is that seen in U.S. Pat. No. 4,294,332, in which rectangular scaffolding sections may be built up alongside a platform that climbs the scaffold sections by means of a rack and pinion system. A suspension platform design has also been designed, in which chains hooked to the scaffold section, or towers, serves to raise the platform.
Safety is of paramount concern when working from an elevated, or suspended, work platform. Prior art devices share many severe safety shortcomings. Firstly, modular sections should be easily raised and locked into position from inside the relative safety of the work platform. Such modular sections should be easily connected by secure, yet easily releasable connections that do not require a worker to struggle or lean outside of the work platform boundary. Secondly, the modular sections must be readily attachable to the vertical surface alongside of which the sections, or towers, are erected, in order to allow significant height to be achieved safely. Thirdly, redundant safety systems are highly desirable, to prevent the work platform from accidentally falling in case of equipment malfunction such as a separation of the hoisting and safety locking mechanism into separate components, and most desirably with more than a single safety lock system.
What has been missing in the art has been a system by which a self erecting work platform may be raised on a tower system of easily interlocking sections, all of which may be easily raised from within the safety of the work platform, and which utilizes a motor and cable lift to raise and lower the platform system that is entirely separate from the safety lock mechanisms that operate to lock the work platform in place while tower sections are being added or removed.